1. Create new java project and add ClassA:

//============================
package javaapplication3;

public class ClassA {
    public String myText = "aaa";
    public void m(){
      myText = "";
      String s = "text";
      System.out.println(s);
    }
}
//============================

2. Select "text" (part of: String s = "text";) and using Alt+Enter invoke Introduce Parameter dialog

3. Type Name: myText and press Refactor

>> new parameter have been introduced, but sentence of code have been changed (see attachment files)